In vitro development of canine somatic cell nuclear transfer embryos in different culture media

The objective of the present study was to investigate the effects of three different culture media on the development of canine somatic cell nuclear transfer (SCNT) embryos. Canine cloned embryos were cultured in modified synthetic oviductal fluid (mSOF), porcine zygote medium-3 (PZM-3), or G1/G2 sequential media. Our results showed that the G1/G2 media yielded significantly higher morula and blastocyst development in canine SCNT embryos (26.1% and 7.8%, respectively) compared to PZM-3 (8.5% and 0%) or mSOF (2.3% and 0%) media. In conclusion, this study suggests that blastocysts can be produced more efficiently using G1/G2 media to culture canine SCNT embryos.

Intrapancreatic ectopic splenic tissue found in a cloned miniature pig

Somatic cell nuclear transfer (SCNT) is a cost-effective technique for producing transgenic pigs. However, abnormalities in the cloned pigs might prevent use these animals for clinical applications or disease modeling. In the present study, we generated several cloned pigs. One of the pigs was found to have intrapancreatic ectopic splenic tissue during histopathology analysis although this animal was grossly normal and genetically identical to the other cloned pigs. Ectopic splenic tissue in the pancreas is very rare, especially in animals. To the best of our knowledge, this is the first such report for cloned pigs.

Rapamycin treatment during in vitro maturation of oocytes improves embryonic development after parthenogenesis and somatic cell nuclear transfer in pigs

This study was conducted to investigate the effects of rapamycin treatment during in vitro maturation (IVM) on oocyte maturation and embryonic development after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT) in pigs. Morphologically good (MGCOCs) and poor oocytes (MPCOCs) were untreated or treated with 1 nM rapamycin during 0-22 h, 22-42 h, or 0-42 h of IVM. Rapamycin had no significant effects on nuclear maturation and blastocyst formation after PA of MGCOCs. Blastocyst formation after PA was significantly increased by rapamycin treatment during 22-42 h and 0-42 h (46.6% and 46.5%, respectively) relative to the control (33.3%) and 0-22 h groups (38.6%) in MPCOCs. In SCNT, blastocyst formation tended to increase in MPCOCs treated with rapamycin during 0-42 h of IVM relative to untreated oocytes (20.3% vs. 14.3%, 0.05 < p < 0.1), while no improvement was observed in MGCOCs. Gene expression analysis revealed that transcript abundance of Beclin 1 and microtubule-associated protein 1 light chain 3 mRNAs was significantly increased in MPCOCs by rapamycin relative to the control. Our results demonstrated that autophagy induction by rapamycin during IVM improved developmental competence of oocytes derived from MPCOCs.

Identification of abnormal gene expression in bovine transgenic somatic cell nuclear transfer embryos

This study was conducted to investigate the expression of three genes related to early embryonic development in bovine transgenic cloned embryos. To accomplish this, development of bovine transgenic somatic cell nuclear transfer (SCNT) embryos was compared with non-transgenic embryos. Next, mRNA transcription of three specific genes (DNMT1, Hsp 70.1, and Mash2) related to early embryo development in transgenic SCNT embryos was compared between transgenic and non-transgenic SCNTs, parthenogenetic embryos, and in vitro fertilization (IVF) embryos. Transgenic SCNT embryos showed significantly lower rates of development to the blastocyst stage than non-transgenic ones. To investigate normal gene expression, RNA was extracted from ten blastocysts derived from parthenogenesis, IVF, non-transgenic, and transgenic SCNT embryos and reverse-transcribed to synthesize cDNA. The cDNA was then subjected to PCR amplification and semi-quantified. More DNMT1 mRNA was detected in the transgenic SCNT group than the other three groups. Hsp 70.1 mRNA was detected in the IVF embryos, while lower levels were found in SCNT and parthenogenetic embryos. Mash2 mRNA was present at the highest levels in transgenic SCNT embryos. In conclusion, the higher levels of methylation and lower protein synthesis after heat shock in the transgenic SCNT embryos expected based on our results may cause lower embryonic development.

Insights on bovine genetic engineering and cloning / Experiências em clonagem e transgenia em bovinos

Transgenic technology has become an essential tool for the development of animal biotechnologies, and animal cloning through somatic cell nuclear transfer (SCNT) enabled the generation of genetically modified animals utilizing previously modified and selected cell lineages as nuclei donors, assuring therefore the generation of homogeneous herds expressing the desired modification. The present study aimed to discuss the use of SCNT as an important methodology for the production of transgenic herds, and also some recent insights on genetic modification of nuclei donors and possible effects of gene induction of pluripotency on SCNT.

Tecnologias de modificação genética têm se tornado ferramentas essenciais para o desenvolvimento de biotecnologias animais. A clonagem animal mediante transferência nuclear de célula somática (TNCS) possibilitou a geração de animais geneticamente modificados através da utilização de linhagens celulares previamente modificadas e selecionadas como doadoras de núcleo, garantindo desta maneira a geração de rebanhos homogênoes expressando a modificação desejada. O presente estudo objetivou discutir o uso da TNCS como importante metodologia para a produção de rebanhos transgênicos, assim como experiências recentes na manipulação genética de células doadoras de núcleo e possíveis efeitos da indução gênica à pluripotência na TNCS.

Culture medium composition affects the gene expression pattern and in vitro development potential of bovine somatic cell nuclear transfer (SCNT) embryos

Different culture systems have been studied that support development of somatic cell nuclear transfer (SCNT) embryos up to the blastocyst stage. However, the use of sequential and two-step culture systems has been less studied. The objective of the present study was to examine the developmental potential and quality of bovine SCNT embryos cultured in different two-step culture media based on KSOM, SOF and the macromolecules FBS and BSA (K-K/FBS, K-S/BSA and K-K/BSA, respectively). No differences were observed in the cleavage rate for any of the culture systems. However, there was a significant difference (P<0.01) in the rate of blastocyst development, with the K-K/ FBS culture system yielding a higher rate of blastocysts (28%) compared to other treatments (18 and 15%, for K-S/BSA and K-K/BSA, respectively). Although quality of embryos, as assessed by the total number of cells, was not different, the apoptosis index was significantly affected in the sequential culture system (K-S/BSA). Gene expression analysis showed alterations of DNMT1, IGF2, LIF, and PRDX6 genes in embryos cultured in K-S/FBS and of SOD2 in embryos cultured in K-K/BSA. In conclusion, we demonstrated that culture medium may affect not only the developmental potential of SCNT embryos but also, more importantly, the gene expression pattern and apoptotic index, presenting the possibility to manipulate the culture medium composition to modulate global gene expression and improve the overall efficiency of this technique.

Mitochondrial and DNA damage in bovine somatic cell nuclear transfer embryos

The generation of reactive oxygen species (ROS) and subsequent mitochondrial and DNA damage in bovine somatic cell nuclear transfer (SCNT) embryos were examined. Bovine enucleated oocytes were electrofused with donor cells and then activated by a combination of Ca-ionophore and 6-dimethylaminopurine culture. The H2O2 and .OH radical levels, mitochondrial morphology and membrane potential (DeltaPsi), and DNA fragmentation of SCNT and in vitro fertilized (IVF) embryos at the zygote stage were analyzed. The H2O2 (35.6 +/- 1.1 pixels/embryo) and .OH radical levels (44.6 +/- 1.2 pixels/embryo) of SCNT embryos were significantly higher than those of IVF embryos (19.2 +/- 1.5 and 23.8 +/- 1.8 pixels/embryo, respectively, p < 0.05). The mitochondria morphology of SCNT embryos was diffused within the cytoplasm. The DeltaPsi of SCNT embryos was significantly lower (p < 0.05) than that of IVF embryos (0.95 +/- 0.04 vs. 1.21 +/- 0.06, red/green). Moreover, the comet tail length of SCNT embryos was longer than that of IVF embryos (515.5 +/- 26.4 microm vs. 425.6 +/- 25.0 microm, p < 0.05). These results indicate that mitochondrial and DNA damage increased in bovine SCNT embryos, which may have been induced by increased ROS levels.

SRY-positive 78, XY ovotesticular disorder of sex development in a wolf cloned by nuclear transfer

Recently, we reported the three wolves cloning with normal karyotype from somatic cells of endangered male gray wolves (Canis lupus), but one wolf had female external genitalia. In this study, we conducted further clinical, histological, and genetic analyses. This cloned wolf had a normal uterus but developed ovotestis. Through molecular analysis of the SRY gene, a mutation in the coding sequence of SRY gene could be excluded as a cause of intersexuality. This is the first report of a cloned wolf with a 78, XY ovotesticular disorder affecting sexual development characterized by bilateral ovotestes.

Cloned calves derived from somatic cell nuclear transfer embryos cultured in chemically defined medium or modified synthetic oviduct fluid

Somatic cell nuclear transfer (SCNT) is considered to be a critical tool for propagating valuable animals. To determine the productivity calves resulting from embryos derived with different culture media, enucleated oocytes matured in vitro were reconstructed with fetal fibroblasts, fused, and activated. The cloned embryos were cultured in modified synthetic oviduct fluid (mSOF) or a chemically defined medium (CDM) and developmental competence was monitored. After 7 days of culturing, the blastocysts were transferred into the uterine horn of estrus-synchronized recipients. SCNT embryos that were cultured in mSOF or CDM developed to the blastocysts stages at similar rates (26.6% vs. 22.5%, respectively). A total of 67 preimplantational stage embryos were transferred into 34 recipients and six cloned calves were born by caesarean section, or assisted or natural delivery. Survival of transferred blastocysts to live cloned calves in the mSOF and the CDM was 18.5% (to recipients), 9.6% (to blastocysts) and 42.9% (to recipients), 20.0% (to blastocysts), respectively. DNA analysis showed that all cloned calves were genetically identical to the donor cells. These results demonstrate that SCNT embryos cultured in CDM showed higher viability as judged by survival of the calves that came to term compared to blastocysts derived from mSOF cultures.

Post-mortem re-cloning of a transgenic red fluorescent protein dog

Recently, the world's first transgenic dogs were produced by somatic cell nuclear transfer. However, cellular senescence is a major limiting factor for producing more advanced transgenic dogs. To overcome this obstacle, we rejuvenated transgenic cells using a re-cloning technique. Fibroblasts from post-mortem red fluorescent protein (RFP) dog were reconstructed with in vivo matured oocytes and transferred into 10 surrogate dogs. One puppy was produced and confirmed as a re-cloned dog. Although the puppy was lost during birth, we successfully established a rejuvenated fibroblast cell line from this animal. The cell line was found to stably express RFP and is ready for additional genetic modification.

Microtubule distribution in somatic cell nuclear transfer bovine embryos following control of nuclear remodeling type

This study was conducted to evaluate the microtubule distribution following control of nuclear remodeling by treatment of bovine somatic cell nuclear transfer (SCNT) embryos with caffeine or roscovitine. Bovine somatic cells were fused to enucleated oocytes treated with either 5 mM caffeine or 150 micrometer roscovitine to control the type of nuclear remodeling. The proportion of embryos that underwent premature chromosome condensation (PCC) was increased by caffeine treatment but was reduced by roscovitine treatment (p < 0.05). The microtubule organization was examined by immunostaining beta- and gamma-tubulins at 15 min, 3 h, and 20 h of fusion using laser scanning confocal microscopy. The gamma-tubulin foci inherited from the donor centrosome were observed in most of the SCNT embryos at 15 min of fusion (91.3%) and most of them did not disappear until 3 h after fusion, regardless of treatment (82.9-87.2%). A significantly high proportion of embryos showing an abnormal chromosome or microtubule distribution was observed in the roscovitine-treated group (40.0%, p < 0.05) compared to the caffeine-treated group (22.1%). In conclusion, PCC is a favorable condition for the normal organization of microtubules, and inhibition of PCC can cause abnormal mitotic division of bovine SCNT embryos by causing microtubule dysfunction.

Patologia de neonatos bovinos originados por meio da técnica de transferência nuclear de células somáticas: clonagem / Pathology of bovine neonates generated by somatic cell nuclear transfer: cloning

Os mecanismos de morte em animais clonados a partir de células somáticas são poucos elucidados. Malformações de órgãos, alterações de tamanho e peso desses animais foram anomalias já descritas, porém em casos isolados. Desse modo, estudos nos níveis anátomo e histopatológicos são de suma importância para ajudar a compreensão dos fatores responsáveis pelos altos índices de insucessos com a utilização da TNCS (transferência nuclear de células somáticas). Assim, o presente trabalho foi realizado com o objetivo de descrever, por meio de exames anatomopatológicos, as alterações presentes em um grupo de animais gerados por TNCS, que vieram a óbito entre 1 e 19 dias de vida. Esse experimento foi realizado entre os anos de 2004 e 2008 na fazenda Tambaú, cidade de Tambaú, Estado de São Paulo. No total foram gerados 21 animais da raça Nelore (Bos indicus), sendo que 11 vieram a óbito e dez apresentaram boa evolução clínica no período perinatal. Foram realizadas as necropsias dos animais e posterior análise histopatológica de tecidos alterados. Esse estudo mostrou alta prevalência de alterações cardiopulmonares, que provavelmente foram determinantes nos mecanismos de morte dos animais. Dentre essas alterações a hipertensão pulmonar e modificações hemodinâmicas diagnosticadas através do exame histopatológico foram as mais frequentes.

The death mechanisms in cloned animals are not well elucidated. There are few cases describing organ malformation, size and weight alterations in these animals. Pathologic studies are necessary to understand the high level of unsuccessful results using the NTSC (nuclear transfer somatic cell) technique. The present study was carried out to describe alterations present in a group of animals generated by NTSC technique that deceased between 0 to 19 days of life, using anatomopathologic examination. This experiment was conducted at Tambaú Farm in São Paulo State between years 2004 and 2008. Initially there were twenty one Nelore breed Bos indicus animals, but 11 of them deceased and ten survived and showed satisfactory clinical evolution in perinatal period. Animals necropsies and histopathologic analyses where performed. The results revealed a high prevalence of cardiopulmonary alterations, which were predominantly lung hypertension and hemodynamic profile changes, revealed by histopathologic analyses.

Production of cloned sei whale (Balaenoptera borealis) embryos by interspecies somatic cell nuclear transfer using enucleated pig oocytes

In this study, we examined the feasibility of using subzonal cell injection with electrofusion for interspecies somatic cell nuclear transfer (iSCNT) to produce sei whale embryos and to improve their developmental capacity by investigating the effect of osmolarity and macromolecules in the culture medium on the in vitro developmental capacity. Hybrid embryos produced by the electrofusion of fetal whale fibroblasts with enucleated porcine oocytes were cultured in modified porcine zygote medium-3 to examine the effects of osmolarity and fetal serum on their in vitro developmental capacity. More than 66% of the whale somatic cells successfully fused with the porcine oocytes following electrofusion. A portion (60~81%) of the iSCNT whale embryos developed to the two- to four-cell stages, but no embryos were able to reach the blastocyst stage. This developmental arrest was not overcome by increasing the osmolarity of the medium to 360 mOsm or by the addition of fetal bovine or fetal whale serum. Our results demonstrate that sei whale-porcine hybrid embryos may be produced by SCNT using subzonal injection and electrofusion. The pig oocytes partly supported the remodeling and reprogramming of the sei whale somatic cell nuclei, but they were unable to support the development of iSCNT whale embryos to the blastocyst stage.

Autologous somatic cell nuclear transfer in pigs using recipient oocytes and donor cells from the same animal

The objective of the present study was to examine the feasibility of the production of autologous porcine somatic cell nuclear transfer (SCNT) blastocysts using oocytes and donor cells from slaughtered ovaries. Therefore, we attempted to optimize autologous SCNT by examining the effects of electrical fusion conditions and donor cell type on cell fusion and the development of SCNT embryos. Four types of donor cells were used: 1) denuded cumulus cells (DCCs) collected from in vitro-matured (IVM) oocytes; 2) cumulus cells collected from oocytes after 22 h of IVM and cultured for 18 h (CCCs); 3) follicular cells obtained from follicular contents and cultured for 40 h (CFCs); and 4) adult skin fibroblasts. The DCCs showed a significantly (p > 0.01) lower rate of fusion than the CCCs when two pulses of 170 V/mm DC were applied for 50 microsec (19 +/- 2% vs. 77 +/- 3%). The rate of DCC fusion with oocytes was increased by the application of two DC pulses of 190 V/mm for 30 microsec, although this was still lower than the rate of fusion in the CCCs (33 +/- 1% vs. 80 +/- 2%). The rates of cleavage (57 +/- 5%) and blastocyst formation (1 +/- 1%) in the DCC-derived embryos did not differ from those (55 +/- 6% and 3 +/- 1%, respectively) in the CCC-derived SCNT embryos. Autologous SCNT embryos derived from CFCs (5 +/- 2%) showed higher levels of blastocyst formation (p > 0.01) than CCC-derived autologous SCNT embryos (1 +/- 0%). In conclusion, the results of the present study show that culturing cumulus and follicular cells before SCNT enhances cell fusion with oocytes and that CFCs are superior to CCCs in the production of higher numbers of autologous SCNT blastocysts.

Modification of maturation condition improves oocyte maturation and in vitro development of somatic cell nuclear transfer pig embryos

This study examined effects on the developmental competence of pig oocytes after somatic cell nuclear transfer (SCNT) or parthenogenetic activation (PA) of : 1) co-culturing of oocytes with follicular shell pieces (FSP) during in vitro maturation (IVM); 2) different durations of maturation; and 3) defined maturation medium supplemented with polyvinyl alcohol (PVA; control), pig follicular fluid (pFF), cysteamine (CYS), or beta-mercaptoethanol (beta-ME). The proportion of metaphase II oocytes was increased (p < 0.05) by co-culturing with FSP compared to control oocytes (98% vs. 94%). However, blastocyst formation after SCNT was not improved by FSP coculture (9% vs. 12%). Nuclear maturation of oocytes matured for 39 or 42 h was higher (p < 0.05) than that of oocytes matured for 36 h (95-96% vs. 79%). Cleavage (83%) and blastocyst formation (26%) were significantly higher (p < 0.05) in oocytes matured for 42 h than in other groups. Supplementation of a defined maturation medium with 100 micrometer CYS or 100 micrometer beta-ME showed no stimulatory effect on oocyte maturation, embryo cleavage, or blastocyst formation after PA. beta-ME treatment during IVM decreased embryo cleavage after SCNT compared to pFF or PVA treatments, but no significant difference was found in blastocyst formation (7-16%) among the four treatment groups. The results indicated that maturation of oocytes for 42 h was beneficial for the development of SCNT embryos. Furthermore, the defined maturation system used in this study could support in vitro development of PA or SCNT embryos.